Think
- Cardiac arrest, severe shock, massive PE/RV failure, profound hyperventilation, or leak/disconnect.
- Use waveform shape, pulse/rhythm, perfusion, and clinical context.
Airway of the MonthReview the case. Understand the airway. Build the skill.
Troubleshooting review
Low EtCO₂ can mean low pulmonary blood flow even when the tube is correct.
Clinical review / use limits
Authored by: Airway of the Month education team. Last reviewed: July 2026. Audience: EM learners, faculty, EMS, RT, simulation educators, and airway teams.
Resources · Editorial policy · ACEP intubation policy · AARC 2024 ventilator assessment guideline · ATS 2024 ARDS guideline update